The alloys were irradiated in a high-voltage electron microscope, and  in situ  observations were made of the resultant structural changes. When the Fe-Cr-Ni alloy was irradiated, the nucleation of dislocation loops was followed by void formation. Grain boundary migration also occurred at the same time. Compositional analysis after irradiation, of an area that included migrated grain boundaries, revealed the presence of Ni enrichment and Cr depletion. The grain boundaries tended to migrate towards a coarser facing boundary plane. The same grain boundary migration, and compositional changes at the boundaries, were seen in the case of the Ni-Si alloy. The results suggested that boundary migration and solute redistribution were closely related to irradiation-induced point defect fluxes; especially those of interstitial atoms. The direction of boundary migration depended upon the relationship between the 2 grains.

H.Takahashi, N.Sakaguchi, N.Hashimoto, S.Watanabe: Materials Science Forum, 1996, 207-209, 561-4